Operating means for brakes



July 1, 1930. H. w. c. LIDDIARD 1,769,849

OPERATING MEANS FOR BRAKES Filed July 11, 1927 2 Sheets-Sheet 1 Fig. I.

Inventor"- Hugh \A/ C. Liddiard,

- His Attorney y 1930. H. w. c. LIDDIARD I 3" OPERATING MEANS FOR BRAKESFiled July 11, 1927 2 sums-sum 2 Fig. 2.-

Fig. 3.

Inventor: Hugh W C. Liddiar'd,

His Attorney Patented July 1, 1930 UNITED STATES PATENT OFFICE HUGH W.C. LIDDIARD, OF RUGBY, ENGLAND, ASSIGNOR TO GENERAL ELECTRIC Q COMPANY,A CORPORATION OF NEW YORK OPERATING MEANS FOR BRAKES Application filedJuly 11, 1927, Serial No. 204,785, and in Great Britain August 4, 1928.

This invention relates to operating mechanisms, and particularly to suchas are remotely controlled, and whilst it is not limited in thisrespect, the operating mechanisms,

according to the invention, are primarily applicable for remotelycontrolling, by electrical means, the braking devices of winders,cranes, lifts, and the like. The invention has for its object animproved arrangement by which the braking effort can be controlled froma distance, and applied gradually to any desired extent.

Operating mechanism, acording to the invention, comprises a pivotedlever, connected at one point to the means to be operated, and

at another point to biasing means (for instance, a weight or a spring),and means for moving one of these connection points along the levers, orfor changing the point about which the lever pivots, in order to varythe effect of the bias on the means to be operated.

According to another aspect of the inven tion, the operating mechanismcomprises a 2 pivoted lever, means applying a bias to a point on thelever, and means mounted on the lever for moving the point ofapplication along the lever.

Preferably, the point of application which so is to be moved withrespect to the lever is electrically controlled, as by means of a relay,or a plurality of relays, or by means of an electric motor; thearrangement being such that (for instance, in the case of an electricmotor) the rotation of the motor in one direction moves the point ofapplication away from the pivoting point and in the other directiontowards the pivoting point.

In a preferred arrangement, according to 4 the invention, the bias isapplied to the piv oted lever by means of a weight slidable along thelever.

More specifically, a brake-controlling mechanism, according to theinvention, comprises a pivoted lever connected to operate the brake, anelectric motor fixedly, and a weight slidingly, mounted on the lever onopposite sides of the pivot therefor, means for balancing the lever whenthe weight is in a predetermined position and the brake oil, a

coupling between the motor and weight whereby the weight can be slidalong the lever in either direction according as to the direction ofrotation of the motor, and means for controlling the energization of themotor so as to effect the rotation thereof in a particular direction.

With the arrangements above described, in which the point of applicationis electrically moved along the ivoted lever, additional means areprefera ly provided when a brake is being controlled, for applying thebrake in the event of the failure of the electric supply. A furthernecessary feature is the provision of an automatically-operated c5limit-switch, which is arranged to deenergize the electricmeans when thebias is applied to a predetermined point of the pivoted lever.Furthermore, if the machine which is being controlled by the brakeis-itself electrically operated, it is advisable to provide means forautomatically opening its circuit when the brake is appliedinconsequence of supply-failure as aforesaid.

An arrangement, according to the inven- .55 tion, will now be described,by way of example, in connection with the diagrammatic representation ofFig. 1 of the accompanying drawing, in which Fig. 2 illustrates diagrammatically one method of controlling 1.1., the electric motor shownin Fig. 1, and Fig.

3 shows a modification of the arrangement illustrated by Figs. 1 and 2.

Referring to the drawings, wherein like reference numerals are used, asfar as pos- 3-, sible, to denote similar parts, and particularly to Fig.1, there is shown a rotatable brake wheel or drum 11, havingexternallycontracting brakeshoes 12 operating against its periphery, thebrake-shoes being applied '15 to produce a braking effort through thesystem of lovers 13 when the rod 1 1 is pulled downwardly. The brakeshoes are released in any suitable manner. The rod 14 is connected atits lower end at 15 to the lever 16, shown pivoted at 17. Mounted on thepivoted lever 16 is an electric motor 18, connected by gearing 19 withthe rotatable screw 21 carried in bearings 22 on the pivoted lever 16.This screw is adapted to engage with a nut in the weight 23, which isslidable along the pivoted lever 16 in either direction according as tothe direction of rotation of the screw 21.

Fig. 2 shows one simple arrangement for controlling the motor, whichcomprises a single two-position control switch 2 1- having two operatingpositions through which either of the contactor coils 25 can be closed.The contactor coils control contactor switches 28 respectively, and itwill be noted that the connections of the motor 18 from the mains 27through the two sets of contactor switches 26 are of opposite sense.Consequently, movement of the control switch 24 to the right willenergize the right-hand contactor coil 25, and contactor switches 26 onthe right-hand side, hus driving the motor 18 in one direction, say, forinstance to move the weight 23 to the right (Fig. 1). Movement oi thecontrol switch 2& to the left will effect the corresponding operationnecessary to drive the weight to the left.

lVhen the weight 23 is moved to the right (that is, towards the pivotingpoint 17) to a predetermined position, it just balances the motor 18 anda counter-weight 28, arranged on an extended portion 29 of the pivotedlever, the braking el'lort of the shoes 12 being nil or a minimum inthisposition of the weight 23. Movement of the weight 23 to the leftincreases the braking efi ort of the brake-shoes 12 to an extentdepending on the position of the weight by tending to rotate thepivot-ed lever 16 counter clockwise and thus tending to pull downoperating rod 1%. It will be seen that the pull exerted on the rod 14 bythe weight 23 during the movement of the brake shoes 12 to their appliedposition varies from the minimum to the maximum value when the lever 16rotates counter clockwise to the position shown in F ig. 1.

In order to prevent the over-running of the weight 23, limit-switches,indicated diagrammatically at 30, may be provided at both ends of thepath of travel of the weight 23. These limit-switches preferably operatein the control circuits, as indicated in Fig. 2, though they may bearranged in other ways to effect the opening of the circuit for themotor 18.

In order that such a scheme shall be satisfactory in practice, it isessential to allow for cases in which the supply of power, either in thecontrolling circuits, or in the circuits of the electric motor, shouldrail. In order to deal with this situation, there is shown in Figs. 1and 2 a brake-solenoid 31, which is energized from the mains 27, andwhich normally retains the pivoted bell-crank 32 with its end engagingthe end of the catch 33. Suspended from the catch 33 is a weight 3%, andthe catch 33 is also connected by means of the pivoted lever 35 with thepivoted lever 16, and therefore with the rod 14. In the event of afailure of supply in the mains 27, the brake-solenoid 31 becomesdeenergized, and the bell-crank 32 rotating anti-clockwise disengagesfrom the catch 33, allowing the weight 34: to apply the brake to thedrum 11.

If the main machine with which the brake drum 11 is associated isadapted to be electrically driven, and is supplied from a sourcedili'erent from that for the motor 18, it is essential to ensure that,in the event of the brake being applied to the drum 11 due to failure ofsupply to the motor 18, the circuit for this main machine shall beopened. To provide for this, there is shown in Fig. 1 a t 'ipping device36 operable by the falling of weight 34, which can be arranged in anysuitable way as, for instance, by means of a relay) to effect theopening of the circuit for the main machine.

In Fig. 2 the brake-solenoid 31 is shown connected directly to thesupply circuit 27. It the control circuits through control switch 2 1-were energized from a source difl'erent from 2?, it would obviously benecessary to eilect connections so that, in the event of failure ofsupply in the control circuit, the brake-solenoid 31 would operate inthis case also. Furthermore, if a short-circuit or earth-fault shouldoccur on the control circuits, the fuse or other protective deviceshould be arranged so as to cut off power to the brake-solenoid 31 inorder to trip the $511116.

In the diagrammatic modification illustrated by Fig. 3, means areprovided for producing any degree of braking effort according to theposition of the brake controller. The brake controller represented by 37comprises a plurality of contacts 38, half of which are connected to thecontacts 39, while the other half are connected to the contacts 41.Contacts 39 and 41 are arranged in two parallel lines on the pivotedlever 16, and slidable contacts i2 cooperating respectively therewithare adapted to be moved or oper ated by the weight 23, according to theposition thereof. In circuit with the movable contacts 42 are thecontactor coils 25 respectively and the limit switches 30. Attached tothe handle of the braking controller is the movable contact member 43,which contacts with one less than half of the contacts 38 and isarranged according to its position to make certain of the contacts 3.and 41 alive through the associated contacts 38. If the weight 23,.

and consequently the slidable contacts 42, does not correspond to theposition of the handle of the braking controller, then one of thesliding contacts 42 will be on a contact 39 or 41, as the case may be,which is alive, and the corresponding contactor coil 25 will beenergized, thus setting the motor 18 in motion to move the weight 23,and the sliding contacts 42, in the appropriate direction that it maycorrespond in position to the position of the braking controller. Assoon as this occurs the sliding contacts 42 will rest on seg- 'ments ofthe contacts 39 or 41, which are not alive, thus bringing the motor torest. If the braking controller handle is then moved, one of the controlcircuits will be energized to cause the motor 18 again to move theweight 23 to a position that corresponds to that of the brakingcontroller handle.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In a friction brake, a brake wheel, friction mechanism cooperatingtherewith,means including a system of levers for a plying said frictionmechanism to said whee means associated with certain of the levers ofsaid system for varying the application force of said frictionmechanism, and additional means associated with certain of the levers ofsaid system for applying said friction mechanism to said wheel.

2. In a friction brake, a brake wheel, friction shoes cooperatingtherewith, a system of levers for applying said shoes to said wheel,biasing means associated with certain of said levers for varying theapplication force of said shoes adjustable means cooperating with saidbiasing means for varying the biasing effect thereof, and means forapplying the shoes independently of said biasing means.

3. In a friction brake, a brake wheel, friction shoes cooperatingtherewith, a system of. levers for applying said shoes to said wheel, aweight associated with certain of said levers for biasing the said shoesto the applied position, means for adjusting the position of said weightto vary the. effect thereof on said shoes, and biasing means associatedwith certain of said levers for biasing the said shoes to the appliedposition in case of failure of said adjusting means.

4. In a friction brake, a brake wheel, friction shoes cooperatingtherewith, means including a lever connected to said shoes for applyingsaid shoes to said wheel, a weight mounted on said lever, an electricmotor mounted on said lever for operating said Weight to and from thefulcrum of said lever to vary the effectiveness of the said Weight inapplying a braking force to said wheel through said shoes, a secondweight operably associated with said lever, means for suspending saidweight, and means for releasing said Weight to apply the brake.

5. A brake-controlling mechanism comprising a pivoted lever connected tooperate the brake, an electric motor fixedly and a weight slidinglymounted on the lever on opposite sides of the pivot therefor, means forbalancing the lever when the weight is in a predetermined position andthe brake off, a

! coupling between the motor and weight levers for. applying said shoesto said wheel,

a weight associated with certain of said levers for blasing the shoes tothe applied position, means for adjusting the position of said weight tovary the effect thereof on said shoes, and preselective control meansfor arresting the adjustment of said weight in any one of a plurality ofpositions.

7. In a friction brake, a brake wheel, friction shoes cooperatingtherewith, a system of levers for applying said shoes to said wheel, 1

a weight associated with certain of said levers for biasing the shoes tothe applied position, means for adjusting the position of said Weight tovary the effect thereof on said shoes, and pre-selective control meansfor .l

said adjusting means for arrestin the adj ustment of said weight in anyone of a plurality of positions.

In witness whereof, I have hereunto set my hand this 21st day of June,1927.

HUGH W. C. LIDDIARD.

